[1] The 230.5 cu in (3.78 L) hemi-headed straight-six was introduced in mid-year 1962, and replaced the flathead "6-226" Willys Super Hurricane that was in use since 1954.

[2] Sampietro worked under Donald Healey in Europe and focused on improving power output through better engine breathing.

[4] Six-cylinder versions built after 3 May 1962, received the 230 OHC "Tornado" engine, replacing the 226 L-head "Super Hurricane" I6.

[3] Additionally, many of the parts on the engine were made of aluminum, including the front cover, water pump, valve cover, and intake manifold, weight savings that resulted in a 575-pound (261 kg) engine, or about 40 pounds (18 kg) less than the previous "6-226" Super Hurricane.

The arrangement proved too rigid for the timing chain gasket, leading to compromise, oil loss, and engine failure.

[9] On the other hand, military versions of the pickup, the M-715 and the M-725, produced between 1967 and 1969, were designed with regular block-mounted motor mounts.

Road tests of the new Jeep Wagoneer by Car Life magazine described the OHC six as "commendably smooth and quiet.

"[13] The engine accelerated the four-wheel-drive full-size station wagon (the SUV designation was not yet known) with an automatic transmission from 0 to 60 mph in 15.9 seconds.

The OHC engine was used in a variety of Jeep vehicles as well as American Motors Corporation (AMC) passenger cars that were assembled under license.

It also received a significant block and crankshaft refinement that year — seven main bearings instead of the original four, as well as a new cylinder head.

The Torino, Jeeps, AMC vehicles, and the Tornado engine, continued to receive upgrades over the years.